Not able to start websphere portal server 5.1

I have tried to create groups using portal console. After creating some groups, portal server stopped with exception "Could not get the users matching the pattern "usernamexxxx" because of the following exception javax.naming.CommunicationException: "xx.xx.xx.xx". Root exception is java.net.SocketException: Too many open files".

After that it is not getting started and giving exception "java.security.PrivilegedActionException: com.ibm.websphere.management.exception.ConfigServiceException: WKSP0006E Error while saving context StrutsPortlet_PA_1_0_45.ear-java.io.FileNotFoundException: /usr/IBM/WebSphere/AppServer/wstemp/anonymous1216196311936/workspace/cells/<<server name>>/applications/StrutsPortlet_PA_1_0_45.ear/.repositoryContext (A file or directory in the path name does not exist.)".